Do not underestimate the swim or climb. There are multiple ways in which you could come to harm attempting this cache:
This cache has been a long time in the planning. Four years ago, DrT and I swam with tow-floats to The Cow and I climbed up to reconnoitre a hiding place. Eventually, this year I paddleboarded and DrT swam again, waiting at the bottom, close to the smaller Calf Rock.
BradLad thinks that the cache is just about visible with binoculars from the St Agnes quay, but there is no mistaking where it is. The log is a dive slate attached to the rope that ties the obvious wooden pole to a rock high on the ridge of The Cow. At present, a pencil is attached to the slate but it may not last forever, so bring your own pencil (a pen won't write on it.)
I managed to pull the paddleboard onto the rocks but you are not guaranteed to be able to do this, so the cache is best searched for with a back-up teammate. Note that the climb would probably be a T 4.5 even if it wasn't on an island. I recommend bare feet; less comfy but great for grip. My route to the pole was via the northeast face and I could see no other way, but you should assess the climb yourself.
I hid the cache in a flat calm and paddled 500m from the Turk's Head beach, via hugging the coast of Gugh. I do not recommend trying this in any other sea conditions and low tide is probably best, during "slack water".